Clopyralid (3,6-dichloro-2-pyridinecarboxylic acid) is a selective herbicide used for control of broadleaf weeds, especially thistles and clovers.

[2][3] For control of creeping thistle, Cirsium arvense, a noxious, perennial weed, clopyralid is one of the few effective herbicides available.

It is particularly damaging to peas, tomatoes, and sunflowers, and can render potatoes, lettuce, and spinach inedible.

Word quickly spread to other local and state governments, and in 2002, DowAgro, the manufacturer of clopyralid, voluntarily deregistered it for use on domestic lawns in the US[5] and it is banned in several US states, but it is found in consumer products in Europe such as Scotts Verdone Extra and Vitax Lawn Clear 2.

Brand names of clopyralid in the US market include Stinger, Transline, Reclaim,[2][6] Curtail, Confront, Clopyr AG, Lontrel, Millennium Ultra, Millenium Ultra Plus and Redeem.